Linguists have generally accepted that Japanese belongs to the Japonic family, and the only extant "sibling" language of Japanese are the Ryukyuan languages. It is also conjectured that Japanese is probably related to Korean and the Altaic languages, citing grammatical similarities and attributed cognates with Manchurian (Tungustic), Mongolian, and Turkish.
However, Japanese also has a few distinctive features that are similar to Austronesian languages. For example, both Japanese and (AFAIK) Bahasa Indonesia generally lack plural marking, and plurals are is often expressed by reduplication:
- 山 yama "mountain"; 山々 yamayama "many mountains"
- 人 hito "human"; 人々 hitobito "many people"
while in Bahasa Indoensia:
- burung "bird"; burung-burung "birds"
- orang "human"; orang-orang "all the people"
This similarity alone is definitely insufficient to conclude that Japanese is related to Austronesian. However, are there any other grammatical similarities cited to support this claim? Do comparative linguists today tend to credit or discredit this claim?